Swage rifling tool



De@ z2, 1959 Filed Aug. 5, 1954 G. R. DOUGLAS 2,917,808

SWAGE RIFLING TOOL 5 Sheets-Sheet 1 INVENTOR.

i BY GERA Lo l? Daf/ams Dec. 22, 1959 G. R. DOUGLAS swAGE RIFLING Toor.

3 Sheets-Sheet 2 Filed Aug. 5, 1954 JNVENTOR. GfK/Lo Doa/GLAS BY wif/1WDec. 22, 1959 G. R. DOUGLAS 2,917,808

swAGE RIFLING Toor.

Filed Aug. 5, 1954 3 SheelLs--Sheefl 3 INVENTOR. BYGs/PALD A. Douma/7.5

Unite My invention relates to a method of and apparatus for riflingbored gun barrel blanks by plastic deformation of the metal. Morespecifically my invention relates to a new concept in swage riingwhereby through the use of a swage tool of my unique design, excessivefriction and strains which result in galling are overcome without theaddition of any lubricating means except a number of drops of an extremepressure lubricant. Further, by my invention precise control of thepitch of the rifling is made possible since the barrel blank is rotatedabout a non-rotating swage tool during the swaging operation. A tungstencarbide swage tool is used in my invention and the riding producedthereby has proved to be of unexpected and unpredictable superiority,these high results being obtained by a single pass of the swage toolwith no further treatment of substance being required.

For some time now, efforts have been made to perfect' a swage rillingmethod. In a British patent of 1876 to Nobel, No. 11,346, is disclosedperhaps one of the earliest techniques wherein a riding projectile wasshot through a barrel to form an extended grooved counterpart of theriiling of the projectile. Since this early concept, a number ofattempts have been made to overcome the extreme friction and gallingproblem and the diicult problem of forcing the swage tool through thebore of the barrel blank to produce the desired filling. Examples of theattempts made toward this end are shown in the German Voigt patent of1920, No. 356,817; the U.S. Hatcher patent of 1931, No. 1,789,308; theAustralian Holmes patent of 1944, No. 118,255; the U.S. Walker patent of1945, No. 2,383,356; and the U.S. Sampson patent of 1953, No. 2,641,822.

The late patents to Walker and Sampson mentioned above are directed tothe problem of moving the swage tool through the bore to produce riflingconforming to conventional standards without yaw, chatter, or galling.Walker adds a metal plating for a lubricant, and Sampson prefers to dolikewise plus accomplishing the swaging operation in two stages.

By my invention the swaging operation is completed in one stage and nocomplicated lubricating step such as the bore plating with ananti-friction metal is required. Preferably my swage tool has apiston-like pilot, an intermediate portion which forms a lubricantreservoir with the wall of the bore, and a forwardly tapered swageportion which accomplishes the riiiing operation. The pilot ispreferably at the forward end of the swage tool. The forwardly taperedswage portion has a conical Huid lubricant trapping section and acylindrical swaging section. l have discovered that by trapping thelubricant in suitable tine markings in the bore wall, such as normalreamer marks, many, many threads of lubricant are available for theactual swaging operation. I have further discovered that excellentresults are obtainedwhen the longitudinal length of the swage sectionand its inherent bite are minimized. The swage tool States Patent O ICCmay then be held in non-rotative condition and the barrel rotatedtherearound to produce precisely the pitch desired.

It will be appreciated that the exact dimensions of my swage tool arecoordinated with the elastic limit, tensile strength, and ductility ofthe barrel blank. Since deformation of the swage tool is negligible, thedimensions thereof will include a compensation factor which will allowfor the springback or recovery of the metal of the barrel blank afterpassage of the swage tool` through the bore.

In practicing my invention I am able to use the same swage tool for anumber of riding twists in rifles of the same caliber. This is uiniquelyaccomplished by an interconnection of the swage pushing means with abarrel blank turning means which may be adjusted to rotate the barrelblank at varying rates in accordance with the pitch desired. However,for a series of calibers, it is necessary to use a series of push rodswhich actually force the swage tool through the bore and a series ofpush rod guides which maintain proper alignment of the push rod with thebore.

The design of my machine takes into consideration the tremendous torqueproduced as the swage tool is forced through the bore by having thelever arm to the barrel rotating means longer than the lever arm to thepush rod.

It will be readily appreciated that various other structural designs maybe employed to accomplish this end and that obvious designs for multiplebalanced operations will present themselves. j

A rie taken from my production line has achieved a new world record ofaccuracy of performance on a` target, oflicially certified, the recordconsisting of the performance in registered competition in which 10consecutive shots with a .22 caliber center iire rifle were` placed in agroup size of .5276 at 200 yards. The rifling of a production line riflebarrel of my invention receives no further treatment of any kind afterthe one pass swaging operation of the instant invention. The barrel usedin establishing the above record received no special treatment.

Other important objects and advantageous features of my invention willbe apparent from the following description and accompanying drawings,wherein, for purposes of illustration herein, a specific embodiment ofmy invention is set forth in detail, and wherein: i

Fig. l is a side elevation of the swage tool of my invention with theimportant small dimensional` varia-` tions enlarged for clarity;

Fig. 2 is an end view of Fig. 1 with dimensional varia-` tions enlargedfor clarity;

Fig. 3 is a side elevation of the swage tool in a bored barrel blankwhich is shown in section with normal` reamer marks enlarged for clarityin the bore and tool dimensional variations enlarged for clarity;

Fig. 4 is a greatly enlarged view of the portion of Fig. 3 within thedotted line rectangle 4-4 showing the trapping of lubricant in theenlarged reamer marks;

Fig. 5 is a side elevation of the machine of my in- Ventron;

Fig. 6 is a plan View taken on line 6 6 of Fig. 5" showing a portion ofthe gear train;

Fig. 7 is an enlarged sectional View taken on line 7-7 of Fig. 5; and lj Fig. 8 is an enlarged side view partly in section showing the meansfor holding the rearward end of the barrel ,i bunk in the Spindle chuckofthe head stock.

The swage tool 14 of my invention, which is shown in `Figs. l-4,preferably includes at its forward end a plston-like pilot 15, anintermediate portion. 1,6rear-tliy wardly of and of less diameter thanthe pilot, a forwardly tapered swage portion 17 rearwardly of theintermediate portion, and a rearward cylindrical end 18.

. The pilot 15 is tapered at its forward end to facilitate insertioninto the bore 21 of a barrel blank 19 and the diameter of the pilot is.001 inch less than the diameter of the bore to facilitate the guidingof the swage tool without detrimental yawing or chattering thereof. Thepilot is approximately 40 percent of the length of the swage tool and ishighly polished.

The cylindrical intermediate portion 16, which is approximately 30percent of the length of the swage tool 1g4, has a diameter of .O20-.040inch less than the bore 21 to form with the wall of the bore an annularreservoir 20 for a uid lubricant remaining after passage of the pilot15.

The forwardly tapered swage portion 17 is made up of a conical iiuidlubricant trapping section 22 and a cylindrical swage section 23. Thecylindrical swage section 23 hasa number of equally spaced helicoidalgrooveforming runners 24 and land-forming grooves 25 which are .002 to.005 inch deep depending on the caliber of the barrel with an allowancemade for spring-back and the like.` In the embodiment shown there aresix equally spaced grooves 25, the side walls of each groove forming anangle of 70 degrees. The transverse peripheral dimension of the arcuatesurface of each of the runners 24 is about 21/2 times the outertransverse peripheral dimension of each of the grooves 25. The runners24 have a radius which forms the finished riiling groove in the barrel4Vblank with an allowance for spring-back of the barrel metal, and thegrooves 24 have a radius to their bottoms equal to the desired borediameter of the ritle barrel plus the spring-back allowance. Throughexperimentation, I have discovered that for all calibers from .22 to .30the longitudinal length of the cylindrical swage section 23 ispreferably .050 to .O90 inch. This, percent` agewise, is substantially lpercent of the length of the swage tool 14. The conical lubricanttrapping section 22 is preferably l5 percent of the length of the swagetool. T he forwardly tapered swage portion 17 is very highly polished toproduce an ultimate surface finish and an infinite blend of the conicallubricant trapping section 22 with the cylindrical swage section 23whereby disernment of the two sections 22 and 23 is impossible. As seenin Fig. 1, the swage section grooves 25 extend a slight amount into thelubricant trapping section 22.

The rearward cylindrical end 18, which is about 5- percent of the lengthof the swage tool 14, has a diameter of 0.002 inch less than the bore21. I have discovered that the rear edges of the runners 24 do notfracture, even under the most extreme conditions, by this design. Aspherical seat 26 is formed in the face of the rearward end 18, thediameter thereof being approximately 70 percent of the diameter of thebore.

I` have discovered that unexpectedly and unpredicably superior resultsmay be attained through the use of a swage tool in accordance with theabove-described design. Further, I have discovered that the ultimate ofresults is obtained by the use of a swage tool of tungsten carbide. Inmy tungsten carbide swage tool, the grooves 25 are preferably ground inat the desired angle; the wall of' the pilot 15 is highly polished bythe use of 8,000 grit diamond; and the lubricant trapping section 22 andthe swage section 23 may be similarly polished but to a much higheriinish. Actual use has shown that a swage tool manufactured and polishedin this fashion has a long life and when properly used with a suitablelubricant completely eliminates all galling problems and nulliiies anytendency of the swage tool to yaw or chatter in the barrel blank bore.

As seen in Fig. 3, a swage tool 14 is inserted in a barrel blank 19 andpushed therethrough by means of a hardened, ground and polished push rod27 which is preferably about 36 inches long and has a diameter ofaart/,see

approximately .004 inch less than the bore of the barrel blank 19. Thebore 21 of the barrel blank, as shown in Fig. 3 and enlarged in Fig. 4,has a series of irregularities or normal reamer marks 28 on the Wallthereof which have been greatly enlarged for clarity and which areestimated as having a depth of approximately .0005 inch. The extremelyfine tool marks 28 are substantially spiral and continuous in nature.The pilot 15 contacts the outer peripheral edges of some of these toolmarks and thereby guides the swage tool centrally through the bore inthe barrel blank. Fluid lubricant remaining after the passage of thepilot 15 is present in the annular lubricant reservoir 20 and a portionof this lubricant is then trapped in the valleys 29 of the tool marks 28by the extremely highly polished conical trapping section 22 of theswage portion 17. These extremely small, substantially spiral-segmentthreads 30 of suitable lubricating material provide the necessarylubrication for the swage section 23 as it passes through the bore 21and causes the metal of the barrel blank to conform with the` runnersand grooves of the swage section by plastic de-v formation. The toolmarks 28 covering the grooves 25 of the swage portion 17 provide areservoir of threadsof lubricating material which further insure properlubricaf tion of the swage section 23 throughout its entire length. Alldimensions of both the barrel blank 19 and the swage-v portion 17 arecarefully determined such that the metal displaced by the runners 24 ofthe swage portion. 17 is'forced to flow into the grooves 25 where it isswaged by the bottom walls of the grooves 25 to form the exftremelysmooth rie lands required in accordance with the conventional linishedstandard. The length of the' swage section is of a predetermined minimumdimen'.-l

sion, preferably .050 to .090 for all calibers from .22 to. 30, tominimize the bite of the runners 24 and thereby minimize the inherentrotative tendency of the swage.

tool on movement through the bore while at the same` time providingrifling in the bore which will conform to the conventional finishedstandard without further treatment of any kind.

The overall length of the swage tool is preferably 16 to 7A; inch forall calibers.

As willl be explained hereinafter, the push rod 27 is moved'with greatforce into face-to-face abutting frictional engagement with thespherical seat 26 of the rearward endv 18 of the swage tool 14. Theforce is tremendous and the frictional engagement between the swage toolseat 26 and the spherical ended push rod 27 is suicient to over-- comecompletely the minimized inherent rotative tendency of the swage toolwhereby during travel of the swage tool through the bore of the barrelblank 19 no rotation occurs. The desired pitch of the rifling isaccomplished,

through the precise rotation of the barrel blank by means to bedescribed. This feature makes it unnecessary'toy employ, more than oneswage tool for a given rifle caliber,

as all riing of various twists normally used can be made. with one swagetool, due to the short bite of the runnersi 24 of the swage tool in thebarrel blank metal. In practice it has been found that the varied pitchrifling produced by rotation of the barrel blank at various speeds hasbeen` extremely satisfactory and well above the conventional finishedstandard.

in Figs. 5-8. Referring now to Fig. 5 it will be seen that' a base frame31 supports a head stock 32 in which the barrel blank 19 is mountedwithin a spindle 33 which is in turn held in a spindle chuck 34. Alignedwith; the; boredbarrel blank 19 is a push rod guide 35 which, as.-

seen in Fig. 7, has an-open top keyhole slot 36 in which is slidablymounted the push rod 27, the longitudinal cerrtral axis of the push rod27 being a perfectly aligned ex-Y tension of the longitudinal centralaxis in the bore of theV barrel blank 19. The enlarged circular portion37 of the 5. keyhole slot 36 is of a diameter equal to the bore of thebarrel blank and provides substantially the same clearance for the pushrod 27 as exists within the bore of the barrel blank. The parallelwalled portion 38 of the keyhole slot 36 has a width of approximately 75percent of the enlarged circular portion of the keyhole slot.

As seen in Figs. and 7 one end of the transverse member 39 is a swagetool pushing end 42 which extends transversely into the keyhole slot 36and has a spherical seat 40in its forward face which receives the rearspherical end 41 of the push rod 27, this frictional, face-to-faceabutting engagement being similar to that previously described betweenthe forward end of the push rod and the swage tool and capable ofcompletely overcoming any rotative tendency of the swage tool and pushrod.

The transverse member 39 is rigidly mounted to a ram 43 of a hydrauliccylinder 44, the hydraulic cylinder being supplied with the necessaryhydraulic uid power by suitable pump and control means not shown. Theother end of the transverse member 39, which is the barrel blankrotating end 45, is bolted to a drive bar 46 of considerable lengthwhich is supported in a suitable rearward guide 47 and forward guide 48.At the forward end of the drive bar as shown in Fig. 6, there is a rack49 which is arranged operatively to engage a change gear 50 of the geartrain which rotates the barre] blank in the required predeterminedfashion to produce the desired rifiing. As seen in Figs. 5 and 6, thegear train includes the change gear 50, and idler gear 51 affixed to andabove the change gear 50 which turns a vertical shaft gear 52, thevertical shaft 53 and the miter gear 54, the miter gear 54 turning asecond miter gear 55, a horizontal shaft 56, and an idler 57, the idler57 then turning the spindle gear 58 which rotates the spindle 33. Thebarrel blank 19 is rigidly held in the spindle 33 by means of a splitcollet 59 in the spindle chuck 34 and a standard 3-jaw universal chuck60. As seen in Fig. 6 the bottom change gear 50 and its top idler gear51 are mounted on a swinging arm 61. The arm 61 has an arcuate slot 62therein whereby suitable swinging adjustment through handle 64 about thevertical shaft 53 is allowed for substitution of the change gear 50 whena different rie pitch is desired. A lock nut 63 secures the arm 61 inthe desired position.

It will be noted in Fig. 5 that the distance from the ram 43 to drivebar 46 is about twice as much as the distance from the ram 43 to thepush rod 27, this 2 to 1 lever arm ratio tending to equalize the torquesinvolved.

As seen in Fig. 8 the barrel blank 19 is turned to a predeterminedoutside diameter larger than the desired iinished ritied barrel and hasan integral collar 65 on the rearward end portion which abuts the splitcollet 59 in the spindle chuck 34, the spindle chuck having a taperedhole which receives the tapered shoulders on the collet to align thebarrel blank with the push rod 27 whereby the longitudinal central axisof the bore of the barrel blank is aligned with the longitudinal centralaxis of the push rod 27. As previously mentioned, the other or forwardend of the barrel blank 19 is held in standard 3-jaw universal chuck 60which maintains the alignment.

In the production of ritling in a previously turned barrel blank havingan annular shoulder at one end and a reamed bore therethrough, asuitable lubricant is deposited in the bore. In practice it has beenfound that merely pouring 8 to 10 drops of automotive gear lubricantsuch as: (Pennzoil Gear Lubricant No. 612 or 614 S.A.E. No.-9) into theforward end of the bore gives excellent results. The swage tool 14 isthen inserted into the forward end of the bore with the pilot 15forward. The barrel blank and swage tool assembly is then insertedthrough the spindle chuck 34 and the split collet 59 placed around thebarrel blank with the collar 65 of the barrel blank 14 resting againstthe face of the split collet. The angular shoulder on the collet 59centers the barrel blank with the push rod 27 and the 3-jaw universalchuck 60 6 may then be tightened up thus holding the barrel blank inproper position in the spindle 33.

The push rod 27 is then moved forward by activation of the hydrauliccylinder 44 which moves ram 43 and transverse member 39, the push rod 27being forced into face-to-face frictional engagement at its forwardspherical end with the spherical seat 26 at the rearward end 18 of theswage tool. Further hydraulic power applied to the hydraulic cylinder 44causes the push rod 27 to move the swage tool through the barrel blank19, no rotation of the swage tool occurring since the bite of therunners 24 of the swage tool is at a minimum and the abutting frictionalengagement of the push rod 27 with the swage tool spherical seat 26 andthe spherical seat 40 of the transverse member 39 is sufficient toovercome the remaining inherent rotative tendency of the swage tool. Asthe transverse member 39 moves forwardly during the riing operation, theother end or barrel blank rotating end 45 thereof moves the drive bar46, thereby causing the rack 49 to rotate the change gear 5l) andthrough the gear train thereby impart rotary motion to the barrel blank19. The precise, predetermined rotary motion of the barrel blank inrelation to the forward motion of the swage tool is thus achieved,thereby producing a rilled barrel having a precisely accurate riflingtwist. This swaging operation is a very fast procedure, taking a periodof time of substantially a minute or less.

I claim:

1. A swage tool of tungsten carbide for forming helica1- like rilling ina bored barrel blank comprising a pistonlike pilot of a diameterslightly less than the bore of said blank, an intermediate portionrearwardly of said pilot and of a diameter less than said pilot, and aforwardly tapered swage portion rearwardly of said intermediate portionwith helicoidal groove-forming runners thereon, said runners being of apredetermined radius to produce rifling conforming to the conventionaliinished standard and said runners being of predetermined minimum lengthto substantially eliminate the inherent rotative tendency of the swagetool on movement through the bore of said blank so that the helix may becreated by rotation of the barrel blank without rotation of the swagetool, said intermediate portion forming an annular space with the wallof the bore which traps a fluid lubricant to insure lubrication of saidforwardly tapered swage portion.

2. A swage tool for forming helical-like riing in a bored barrel blankcomprising a portion having a diameter less than the bore of the blankfor guiding the swage tool, and a forwardly tapered swage portion havinghelicoidal groove-forming runners thereon, said runners being of apredetermined radius to produce riding conforming to the conventionalfinished standard and said runners being of a predetermined minimumlength to substantially eliminate the inherent rotative tendency of theswage tool on movement through the bore of the blank so that the helixmay be created by rotation of the barrel blank without rotation of theswage tool.

3. A swage tool in accordance with claim 2 wherein said swage tool is oftungsten carbide and wherein said forwardly tapered swage portionincludes a cylindrical swage section in which said helicoidalgroove-forming runners are formed, said cylindrical swage section beingof a length within the range of .050 to .090 inch.

4. A swage tool of tungsten carbide for forming helicallike rifling in abored barrel blank comprising a portion having a diameter slightly lessthan the bore of the blank for guiding the swage tool through the borewithout yaw or chatter, and a forwardly tapered swage portion having aconical fluid lubricant trapping section and a cylindrical swage sectionrearwardly thereof, said swage section having helicoidal groove-formingrunners thereon, the

References Cited in the le of this patent UNITED STATES PATENTS Castle`uly 28', 1908 Vogt Feb. 4, 1913 Hatcher J an. 20,- 1931 Multhaupt Aug.181, 1931 Walker Aug. 2'1, 1945 Lee Mal'.v 15, 1949 Sampson June`1'6,1953 UNTTED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION December 2.2,1959 'Patent No Q ,9317 808 Gerald R., Douglas It is herebjr certifiedthat error appears in the -printed specification of the above numberedpatent requiring correction and that the said Letters Patent should readas corrected below.

Column 3, line Mw hfor "disernment" read e disoexctnmerlJr m; column 4,line 35, for "30" reed fm 3D me Signed end sealed thier SHQ-th dey o'Mey 1960.,

(SEAL) Attest:

KARL iii, AXLTNE ROBERT C. WATSON Commissioner of Patents AttestingOficer

